A thermal process of device processes includes a plural low-temperature treatments and plural high-temperature treatments. Accordingly, even when an epitaxial wafer is used, oxygen precipitates are formed in a substrate wafer. In the past, the oxygen precipitates were effective for capturing (gettering) metal dopants which may be generated in the process and the formation of the oxygen precipitates was desired.
However, recent device manufacturing processes include a plurality of rapid temperature-rising-and-falling thermal treatment processes and thus a stress load increases in thermal treatment in the device process. Particularly, with the increase in integration of devices, the rapid temperature-rising-and-falling thermal treatment process tends to be further shortened in time and the highest temperature in the rapid temperature-rising-and-falling thermal treatment process tends to be raised. From the 45 nm node (hp 65), annealing processes called FLA (flash lamp annealing), LSA (Laser Spike Anneal), LTP (laser thermal process), and Spike-RTA (Rapid Thermal Annealing) may be used.
In the FLA process among these, a wafer is heated to an initial temperature of 400° C. to 600° C., the entire surface of the wafer is irradiated with light of a short wavelength from an Xe lamp and the like to rapidly heat only the outermost surface layer of the wafer equal to or higher than 1100° C. up to the vicinity of the melting point of silicon, and it is then rapidly cooled. The thermal treatment time is on the order from μ (micro) seconds to milli seconds.
The techniques related to the FLA process are disclosed in Patent Document 1 and Patent Document 2.